Recently, chiefly in multicarrier transmission systems, a method of scheduling users by dividing them into a plurality of blocks along the frequency axis-time axis is proposed. Here, a region stipulated on the frequency axis and the time axis established when a user performs communication is termed an ‘assignment slot’, and a block that forms the base when determining an assignment slot is termed a ‘chunk’.
A method is proposed whereby, when transmitting broadcast/multicast signals and control signals, a wide block is assigned in the frequency direction to obtain frequency diversity, ensuring that errors are unlikely even at low received power. When transmitting a unicast signal, which is a one-to-one communication between terminals functioning as a wireless transmitter and a wireless receiver, a narrow block is assigned in the frequency direction, ensuring that multi-user diversity is obtained.
FIGS. 40 and 41 are diagrams illustrating the relationship between time (vertical axis) and frequency (horizontal axis) of a signal transmitted from a wireless transmitter to a wireless receiver. In the two-dimensional plane formed by the time axis and the frequency axis, the time direction is divided into time widths t1 to t5. The time widths of transmission times t1 to t5 are the same. The frequency axis is divided into frequency widths f1 to f4. The frequency widths of transmission frequencies f1 to first supporting member 4 are the same, namely F.
Using the transmission times t1 to t5 and the transmission frequencies f1 to f4, twenty chunks K1 to K20 are set in the two-dimensional plane formed by the time axis and the frequency axis.
As shown in FIG. 41, for example, four chunks K1 to K4 are joined in the frequency axis direction, and the time axis direction is divided into three equal sections, creating communication slots S1 to S3 having time widths of t1/3 and frequency widths of 4×f1. Slot S is assigned to a first user, slot S2 is assigned to a second user, and slot S3 is assigned to a third user. This enables the first to third users to obtain a frequency diversity effect. Frequency diversity is achieved when transmitting signals from a wireless transmitter including a plurality of transmission antennas to a wireless receiver, by applying a large delay time difference between signals transmitted from the plurality of transmission antennas. Frequency diversity effect is the increase in communication quality that is achieved, utilizing the fact that a large delay time difference is applied between signals transmitted from the plurality of transmission antennas, by using signals in regions of good reception quality at the receiver. A chunk that transmits a signal from the wireless transmitter to the wireless receiver while applying frequency diversity is termed a ‘frequency diversity region’.
Also, for example, chunk K5 is assigned as slot S4 to a fourth user. Chunks K6 and K7 are joined and assigned as slot S5 to a fifth user. Chunk K8 is assigned as slot S6 to a sixth user. This enables the fourth to sixth users to obtain a multi-user diversity effect. Multi-user diversity is achieved when transmitting signals from a wireless transmitter including a plurality of transmission antennas to a wireless receiver, by applying a small delay time difference between signals transmitted from the plurality of transmission antennas. Multi-user diversity effect is the increase in communication quality that is achieved, utilizing the fact that a small delay time difference is applied between the signals transmitted from the plurality of transmission antennas, by using signals in regions where there is little fluctuation in received power. A chunk that transmits a signal from the wireless transmitter to the wireless receiver while applying multi-user diversity is termed a ‘multi-user diversity region’.
Chunks K9 and K11 are, for example, assigned as slot S7 to a seventh user. Chunks K10 and K12 are joined and divided into three equal parts along the time axis, creating communication slots S8 to S10 having time widths of t3/3 and frequency widths of 2×f2. Slot S8 is assigned to an eighth user, slot S8 is assigned to a ninth user, and slot S10 is assigned to a tenth user. This enables the seventh to tenth users to obtain a multi-user diversity effect.
Also, for example, chunk K13 is assigned to an eleventh user as slot S11. Chunk K14 is assigned as slot S12 to a twelfth user. Chunks K5 and K16 are joined, and assigned as slot 813 to a thirteenth user. This enables the eleventh to thirteenth users to obtain a multi-user diversity effect.
Also, for example, chunks K17 and K19 are assigned as slot S14 to a fourteenth user. Chunks K18 and K20 are joined, and divided into three equal parts along the time axis, creating communication slots S15 to S17 having time widths of t5/3 and frequency widths of 2×f2. Slot S15 is assigned to a fifteenth user, slot S16 is assigned to a sixteenth user, and slot S17 is assigned to a seventeenth user. This enables the fifteenth to seventeenth users to obtain a multi-user diversity effect.    Non-Patent Literature 1: 3GPP contribution, R-050249    Non-Patent Literature 2: 3GPP contribution, R1-050590